In the field of injection molding, there are many types of manifold configurations or assemblies. These manifold assemblies are used to maintain the hot molten plastic at a specific temperature throughout the injection of material through the flow path to a mold cavity. The purpose is to ensure that the hot molten plastic material is at a sufficiently high enough temperature when it enters the cavity and does not begin to solidify within the manifold assembly. To this end, the manifold assembly employs one or more nozzle assemblies for introducing to a mold cavity molten resin material. The nozzle assembly receives the molten resin material from a central sprue through a series of passages of a manifold assembly. It is desirable to sufficiently heat the manifold assembly so that the sprue, associated passages, nozzle and nozzle drop tip, which is in direct contact with the mold cavity, will maintain the molten resin at a desired heated temperature.
Typical nozzle assemblies have a nozzle body connected to the sprue and a drop tip nozzle that is connected to the nozzle body. Along the length of the sprue and nozzle assembly, there are a number of heating elements used to input heat to the manifold assembly in order to heat the flow passage for the molten resin. The drop tip nozzle is a separate element that is attached to the nozzle body, usually using a threaded connection. One frequent problem is that mold operators do not wait until the manifold assembly has reached the optimum molding temperature prior to beginning the flow of molten plastic material through the manifold assembly. As a result, some of the molten plastic material will begin to solidify or become more viscous increasing the internal pressure within the flow passages of the manifold assembly to the point that the threaded connection between the drop tip and the nozzle body ruptures and the drop tip will break away from the nozzle body and essentially destroy the nozzle body and drop tip assembly. The present invention provides an improved nozzle and drop tip assembly that is resistant to the greater pressures that are encountered when the manifold assembly has not been heated to the proper operating temperatures.